Deflecting coil



Feb. 8, 1949. I QBERT 2,461,230

DEFLECTING COIL Filed Sept. 4, 1946 HORIZOIWZL IRA/VSVERSE AXIS 0F (MT/ ODE RA) INVENTOR MAXIMILIAN J. OBERT ATTORNEY Patented Feb. 8, 1949 2,461,230

UNITED STATES PATENT OFFICE DEFLECTING COIL Maximilian J. Obert, North Merehantville, N. J., assignor to Radio Corporation of America, a corporation of Delaware Applicationseptember 4, 1946, Serial No. 694,805

7 Claims.

My invention relates in general to electromagnetic apparatus and, more particularly, to such apparatus as is used to accomplish the deflection of an electron beam.

It is common practice to wind electromagnetic coils for deflecting the cathode ray beam in a cathode ray tube with a particular size of conductor. Due to the configuration of the coil itself, and its position about the neck of the tube, the resultant deflecting effect is such that an equal focusing effect on the cathode ray beam is not maintained for all deflected positions thereof. It will be appreciated that in television apparatus the effect on the focus of the cathode ray beam reproducing the televised image, for instance, is important, and the beam should maintain a constant correct focus, or a desired focus, regardless of its point of impingement on the reproducing screen usually associated with this type of tube. Accordingly, it is one of the objects of my invention to provide a deflecting coil or yoke for deilecting a cathode ray beam and which has good deflecting properties and in which deleterious effects on the focusing of the beam during certain portions of its deflection are minimized.

It has been found that if a greater concentration of turns per unit of cross-sectional area of the deflecting coils is concentrated on the outer edge of the coils than the turns per unit crosssectional area on the inner edge of the coil, the focusing characteristics of the coil will be improved, since, With present known kinescope types of tubes, the maximum flux should be concentrated at the outside edge of the coil. Accordingly, it is another of the objects of my invention to provide a deflecting coil for cathode ray apparatus wherein this will be accomplished.

It is a still further object of my invention to provide a deflecting coil which will have as equally a good design from the standpoint of size and shape as those that are used at present but which do not have the improved characteristics of the present invention.

My invention in general contemplates that the coil or yoke will be made by winding the coils with two or more differing sizes of wire, that is to say, wire having two or more differing crosssectional areas. The larger sized Wire may be used for the inner turns and the smaller sized wire may be spliced thereto and the coil wound to its finished form with the smaller sized wire. Presently known tools and techniques may be used to accomplish this end.

My invention will best be understood by referring to the drawings in which:

Figure 1 shows one embodiment of my invention with a deflecting coil partially cut away; and

Figure 2 shows a cross-sectional view of the coil of Figure 1 contained between two cutting planes at right angles to the coil, and a similar section of a second coil co-operatively associated with the first.

Referring to Figure 1, there is shown one em bodiment of my invention with the coil partially cut away for purposes of clarity and convenience. In this figure the cathode ray tube with which the coil is associated is omitted and the relative position of the coil and neck of the tube is indiate in F ure 2. Also for purposes of simplicity, only one coil has been shown in this figure. In this figure, there has been illustrated a coil usin wire having two differing cross-sectional areas. The outer portion of the coil, or that is to say, the portion thereof that sits closest the horizontal transverse axis of the tube neck if the coil be the horizontal deflecting coil, is comprised of wire conductors [2 having a particular cross-sectional area which is relatively small. The inner turns of coil, that is to say the turns that are most remote from the horizontal transverse axis of the tube if the coil be the horizontal deflecting coil, and the vertical transverse axis if it be the vertical deflecting coil, are comprised of a conductor 13 having a cross-sectional area which is different from and some degree heavier than the cross-sectional area of the conductor I2. It will be appreciated that coils using several different sizes of Wire might be used and that the invention is not limited to the use of merely two differing sizes of wire.

The coil so formed can be made to have a general shape such as that shown in the above cross-sectional showing. In practice, each coil has two arm-like members, the extreme edges of which are spaced approximately degrees apart. Each arm has covered an arc of approximately 40 degrees. This may be varied as required to obtain a rectangular raster or picture on the particular kinescope used. In practice, the vertical deflecting coils would be arranged with the arms extending in the opening between the two arms of each coil.

The normal cross-section of the coil is similar to presently used coils and this particular shape lends itself to rapid production and easy and accurate assembly and spacing of interlocking sections. More turns per unit of cross-sectional area will appear on the outside section or edge of th coils than are contained on the inside edge of the coils, thus fulfilling the requirement for improved focus.

Referring to Figure 2, there is shown a crosssectional view of a portion of the apparatus as contained within two cutting planes, each at right angles to the neck of the cathode ray tube and the coil, and spaced apart slightly and contained between the ends of the coil. In this view, the relative position of the deflecting coils and cathode raytube :neck in is shown-as well as the relative position :between the turns 'of the .coil comprised of the fine wire and the turns of the coil comprised of the relatively heavy wire. The two coil assemblies forming the horizontal deflecting coil system are illustrated in this flglll'e, and it will be seen that the inner .wire sections'of the coils are positioned immediatelyadjacenteach other, and the heavier wire sections are positioned remotely from each other.

It will be appreciated that presently known methods and apparatus for coil windinglmay he used in winding the illustrated coil form. The

coilis of the so-called saddle type of deflecting .coil in which therearegtwo active side members .as illustrated whichare separated by a.space inibetween and into which another fsaddle" type .of ,coilmay bejfitted in order to deflectthe cathode ra yfbearn 'innanothercoordina'te of.its'motion.

Coil winding, according to the teachings of 'U. S. Patent ,No..2,448,6.72, issued September '7, 19.48, by Harry V. 'Knauf Jr might be vused orlthe teachings of II. "S. Application Serial No. 631734,

vfiled November '29, I945 by Gustave 'L. Grund- Vmann, could "be used, as 'well ;as other known forms .of coil winding devices and methods.

' Having now described the invention, what is claimed and desired to be secured "by Letters Patent is'the following:

What I'claim is:

1. An electromagnetic :defflecting means 'for cathode'ra'y apparatus -for deflecting the cathode ray beam in one .co-ordinate of movement comprising coil means wound from .a plurality of a coil having the inner turns thereof formed of a conductor having a different cross-sectional area than the conductors forming the outer turns thereof.

4. Apparatus in accordance with claim 3 wherein the inner turns of the coil are formed of a conductor having a cross-sectional area greater than itheiouter turns thereof .5. An {electromagnetic deflecting *means for cathode ray tube apparatus for deflecting the cathode ray beam in one coordinate of its motion comprising a coil member formed of a plurality of :conductors at least one of which has a crosssectionalareadifierin from the other conductors,

.andin which the conductors positioned nearest rthe axis :of the tube corresponding to the coordinate of motion in which the cathode ray beam is -deflected have across-sectional area smaller than the conductors positioned remotely from said axis.

6. An electromagnetic defiectingyoke for .deflecting the cathode ray beam formed within a cathode ray tube in one co-ordinate of movement comprising-a 'coil having anumber of turns per unit of cross-sectional area in one portion thereof greater than the number of turnsper unit 0; cross-sectional -'area"in another portion -there- Apparatusin accordance with-claim G-Wherein the number'of turns periun'it of cross-sectional area in the outer edges of the yoke is greater-than 'the number of turns per unit 'of'cross-sectional -at the inneredgesofthe'yoke.

J. OBERT.

ZCITFEI) The following reierences are of record .in the jfile of this patent:

UNITED PATENTS Number Name Date 928,136 Lacy .July 13, 1909 1;501;'787 Lacy July 15,1924 -1;872;369 *Van Sickle Aug.16,1'932 2243;893 'Blumlein lune.3,1941 2,406,740 Buckbee "Sept.3 ,'1946 254145925 Buckbee Jani28, 194:1

FOREIGN PATENTS Number Coun'try Date 3514,1 70 -:GreatBritain Nov. 1,'1'939 

